Kiln fire. Sterling silver (.925) clay for use in making sterling silver products. Sterling silver is a stronger metal than fine silver. It should be used to make very small or thin metal pieces such as small ring bands. Fire with carbon inside a kiln. This product can also be mixed in equal parts with the fine silver products to achieve ".960 silver". The .960 silver mix will not require a carbon firing, but will still achieve some of the strength of sterling silver.